It is known to divide granular material, such as, for example, cement, cement-containing materials, slag, limestone or else ores, into a coarse and a fine grain fraction by means of a classifier. Such classifiers are customarily placed downstream of a material comminuting apparatus, such as, for example, a roller mill, wherein the coarse material emerging from the classifier is supplied again to the material comminuting apparatus. Known classifiers are, for example, static classifiers in which material is roughly classified via impacting and guiding apparatuses, and dynamic classifiers in which material is finely classified, for example, via a rotating rod basket.
DE 10 2004 027 128 A1 discloses a classifying device which comprises a static classifier and a dynamic classifier, wherein the static classifier forms the first classifying stage and the dynamic classifier forms the second classifying stage.
During the comminuting of material and in particular in cement production, a plurality of grinding operations using different comminuting apparatuses are frequently necessary in order to achieve the desired grain size. A classifying device is customarily connected downstream of each of said comminuting apparatuses.